استعرض مصدر The Relationship between Associative Learning, Transfer Generalization, and Homocysteine Levels in Mild Cognitive Impairment



The Relationship between Associative Learning, Transfer Generalization,
and Homocysteine Levels in Mild Cognitive Impairment

Abeer Mahmoud Eissa, Egypt
Ahmed A. Moustafa1*, Doaa H. Hewedi2
, Abeer M. Eissa2
,
Catherine E. Myers3
, Hisham A. Sadek2

Previous studies have shown that high total homocysteine levels are
associated with Alzheimer’s disease (AD) and mild cognitive impairment (MCI).
Objectives: Prior studies suggest that learning and generalization of learned
rules are subserved by different brain systems, namely the basal ganglia and
hippocampus. In the current study, we test if these cognitive processes are
affected by homocysteine levels in healthy controls and individuals with MCI.

Methods: In this study, we test the relationship between cognitive function and
total homocysteine levels in healthy subjects (Global Dementia Rating, CDR =
0) and individuals with MCI (CDR = 0.5). We have used a cognitive task that
tests learning and generalization of rules, processes that have been
previously shown to rely on the integrity of the striatal and hippocampal
regions, respectively.

Results: We found that total homocysteine levels are higher in MCI individuals
than in healthy controls. Unlike what we expected, we found no difference
between MCI subjects and healthy controls in learning and generalization. We
conducted further analysis after diving MCI subjects in two groups, depending
on their Global Deterioration Scale (GDS) scores: individuals with very mild
cognitive decline (vMCD, GDS = 2) and mild cognitive decline (MCD, GDS =
3). There was no difference among the two MCI and healthy control groups
in learning performance. However, we found that individuals with MCD make
more generalization errors than healthy controls and individuals with vMCD.
We found no difference in the number of generalization errors between healthy
controls and MCI individuals with vMCD. In addition, interestingly, we found
that total homocysteine levels correlate positively with generalization errors, but
not with learning errors.

Conclusion: Our results are in agreement with prior results showing a link
between hippocampal function, generalization performance, and total
homocysteine levels. Importantly, our study is perhaps among the first to test
the relationship between learning (and generalization) of rules and
homocysteine levels in healthy controls and individuals with MCI.

http://www.alz.co.uk/sites/default/files/dubai2013/adi-dubai-2013-abstracts.pdf

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